1. Field of the Invention
This present invention is related to an adjusting apparatus. More specifically, this invention is related to an adjusting apparatus for adjusting the brightness of images.
2. Description of the Prior Art
Generally, images provided by digital cameras and projectors have a problem that the brightness of an image is unequal in different areas; in the same image, areas close to edges are darker, areas close to the center are lighter. This problem makes the image inharmonious and viewers might feel uncomfortable about this condition. Accordingly, how to adjust the brightness of an image such that the brightness in each area of the image is average becomes a critical issue in image processing.
To solve the aforementioned problem, the US 2004/0155970 patent application publication proposes a method of using polynomials. The method first selects one pixel from a plurality of pixels in an image as a reference point. Then, with the reference point, polynomials are used to calculate the brightness of the image. The brightness of the image can be compensated based on the calculated results. Besides, the U.S. Pat. No. 4,884,140 patent proposes a method of using analog circuits to compensate the brightness of an image. The US 2003/0052987 patent application publication proposes a method of using digital circuits to compensate the brightness of an image. The two methods using circuits have more complicated calculations. That is to say, compensating the brightness of an image must be performed with complicated circuits. Furthermore, a large number of multipliers used in the circuits slow down the calculation speed and increase the hardware cost.
As known by people skilled in the art, the prior arts not only use complicated circuits with high cost but also take longer processing time with complicated calculations. Therefore, a major objective of the invention is to provide an adjusting apparatus to overcome the aforementioned problems.